The Japanese operator of a stricken nuclear plant said today it has started dumping a mineral into the sea that absorbs radioactive substances, aiming to slow down contamination of the ocean.

The Japanese operator of a stricken nuclear plant said on Saturday it has started dumping a mineral into the sea that absorbs radioactive substances, aiming to slow down contamination of the ocean.

Tokyo Electric Power Co. (TEPCO) said it had begun dropping zeolite near a water outlet from the Fukushima Daiichi plant -- which has been leaking radiation since it was crippled by a March 11 quake and tsunami -- from Friday.

The mineral has wide-ranging industrial applications, including nuclear waste processing. Officials hope it will help to reduce the spread of radioactive materials from the plant into the Pacific, though the effectiveness of the measure was not yet clear.

The mineral has been used to help mitigate other nuclear accidents, including the 1979 Three Mile Island nuclear accident in the United States.